Tomatoes plants grow best and produce the most generous fruit harvests when allowed to sprawl and bask in the sun. Since tomato fruits are much heavier than the stems and foliage can support in any upright position, staking, trellising and using forms is helpful to give the tomatoes the structural strength they need. Since tomatoes are not natural climbers, ties are used to train the plants onto structures until they are integrated into the structure and can hold themselves in place.
Identify the largest tomato plant stems and stretch them upright against the support structure.
Tie the stalks to the structure in several places to secure them in place with flexible green garden ties or with uncoated cotton string. Make the connection snugly enough to keep the stalks upright but not so tight that the string or ties are tight against or cut into the plant tissue.
Pull up the smaller stems and stalks and tie those onto the support structure, filling in between the large stems. Repeat this process for new stems as they grow long enough to reach the structure.
Cut down the ties at the end of the season with scissors and discard them along with the dead plant material.